The present subject matter relates to the field of recombinant bacteriophage constructs and related heterologous peptide sequences for targeted contraception in animals. In particular, the present subject matter relates to peptides and polypeptides that bind to the zona pellucida (ZP) of oocytes, methods for selecting such peptides and polypeptides, vectors or constructs that express the selected peptides and polypeptides, and compositions that comprise such peptides, polypeptides, vectors or constructs (e.g., compositions for inducing an immune response against sperm).
Overpopulation of animals of multiple species including domestic, feral, and wild animals results in various economic, health, and security problems. For example, dog overpopulation remains a serious welfare concern and is a worldwide problem. In the United States, several million domestic dogs enter animal shelters annually and approximately one half are euthanized. Feral free-roaming dogs throughout the world affect the environment generating tons of waste products, consuming small wildlife, and, most of all, harboring dozens of viral, bacterial and parasitic diseases communicable to humans, agricultural animals, and pets.
With respect to feral dogs, “capture and kill” has been the primary strategy used to control populations. However, this strategy has not reduced the magnitude of this serious problem in 100 years because it illogically addresses the result rather than the cause of the problem. The obvious solution is preventing the birth of unwanted animals. Surgical gonadectomy is considered the gold standard and low cost spay/neuter clinics have made limited progress in reducing unwanted dog populations in some locals, but it is not equal to this overwhelming task. While feral dogs are less of a concern in the United States due to active spay and neuter programs, animal shelters and animal control programs are lacking in many developing countries and humane methods of population control are urgently needed. Clearly, an effective, technically uncomplicated and inexpensive method applied on a mass scale is needed.
Feral swine also present a threat to agricultural crops, soils, vineyards, tree plantings, turf, rare plant communities, wildlife habitat, archaeological sites, and vehicles. (See Ditchkoff S S, West B C. Ecology and management of feral hogs. Human-Wildlife Conflicts 2007; 1(2):149-151). Feral swine compete with livestock and native wildlife for food, and prey on domestic animals and wildlife. Feral swine carry at least thirty important viral and bacterial diseases and thirty-seven parasites that affect humans, pets, livestock, and wildlife (e.g., brucellosis, salmonellosis, diseases due to pathogenic E. coli strains, rabies, tuberculosis, and tularemia). Feral swine also could potentially spread additional human and animal diseases not currently found in the United States. (See Hutton T, DeLiberto T, Owen S, Morrison B. Disease risks associated with increasing feral swine numbers and distribution in the United States. Midwest Association of Fish and Wildlife Agencies 2006). Additional examples of species, the overpopulation of which imposes various kinds of economic and health risks, include coyotes, deer, and raccoons.
Control programs for unwanted animals such as poisoning, trapping, shooting, etc., are ineffective, expensive and generally unacceptable to the public. The most efficient solution worldwide is to prevent the birth of unwanted animals. The development of nonsurgical methods of sterilization would provide practical alternatives to surgical neutering. This could be achieved using effective and economically sound contraceptive preparations. However, currently available contraceptives for animals are not selective and affect multiple species and, therefore, cannot be permitted for use in uncontrolled environments such as natural habitats of feral or wild animals. (See Miller L A, Johns B E, Killian G J. Immunocontraception of white-tailed deer with GnRH vaccine. Am J Reprod Immunol 2000; 44(5):266-274; and Killian G, Miller L, Rhyan J, Doten H. Immunocontraception of Florida feral swine with a single-dose GnRH vaccine. American Journal of Reproductive Immunology 2006; 55:378-384). Thus, there is an urgent need for immunocontraceptive, vaccines that can affect the target species only and be delivered via economically sound administration.